The invention discloses a raw material composition of a fermented milk beverage. The raw material composition comprises the following raw materials in percentage by mass: 35-60% of a fermented milk base material, 0.05-1% of a stabilizing agent, 5-15% of a sweetening agent and the balance of water, wherein the fermented milk base material is prepared through fermentation of raw material milk and lactic acid bacteria, and the stabilizing agent comprises the following components of (a) one, or two or more of sodium carboxymethyl cellulose, propylene glycol alginate, pectin, agar, starch, carrageenin and gellan gum; and (b) one, or two or more of mono(di)glycerin fatty acid ester, acetylated mono(di)glycerin fatty acid ester, and diacetyl tartaric acid ester of mono(di)glycerides. The raw material composition of the fermented milk beverage provided by the technical scheme of the invention is used as a raw material, and kluyveromyces lactis (kluyveromyces lactis) is added for fermentation, so that a gas-containing fermented milk beverage is made. The fermented milk beverage is subjected to secondary fermentation of lactic acid bacteria and microzymes, contains gas produced by natural fermentation, and is high in irritating mouth feel, unique in flavor, and good in stability.